can someone debug this code/function ?

function f = lion(x,A,r1,r2)
y = A\r1;
z = A\r2;
f = (y(1)*x.^2 + y(2)*x).*cos(z(1)*x + z(2));
return;

 A, r1 and r2 are given matrices and y and z are such that Ay = r1 and Az = r2. I am trying to compute the integral of this function using some technique from class. apparently there is somethig=ng wrong with this function.